Partners at the Fraunhofer Institute for Surface Engineering and Thin Films (IST), Germany; MRC Systems GmbH, Germany; BCE Special Ceramics GmbH, Germany; and the Forschungsinstitut Glas/Keramik FGK, Germany, collaborated to develop a robust and application-oriented German industrial standard for characterizing the photocatalytic activity of surfaces.
Photocatalytically active materials or surface coatings enable the self-cleaning effect when light of the appropriate wavelength falls on the photocatalytically active surface, decomposing organic contaminants. The light also causes a secondary effect, “hydrophilization” of the surface, making it “water-loving”. Water forms a film on the surface that can infiltrate dirt particles, enabling them to be rinsed off more easily. Self-cleaning surfaces can not only make everyday tasks much easier but also prolong the service life of the products.
In order to compare the photocatalytic activity of different products, the German industrial standard DIN 52980:2008 applies. It calls for verification via the degradation of methylene blue. In the past, strong fluctuations of the measurement results occurred repeatedly in practice, and a number of weak points in the current method have also been pinpointed in the scientific literature.
In a research project funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), the partners examined the specifications of the previous measurement methodology and subsequently formulated proposals for adaptations and amendments in a draft revision of the standard.
In addition to a new procedure for large-format samples, new standards were developed, characterized and investigated with regard to their reusability. They are composed of long-term stable ceramics with defined graded photocatalytic coating.
A round-robin test coordinated by the Fraunhofer IST shows the measurement results using the new application-oriented standard and the new test methods are significantly more precise and reliable than with the original procedure. Coefficient of variation of the reproducibility is now only 4.95% as opposed to the original 30.6%.
Image – Prototype of the measuring facility for large-format samples. Courtesy of MRC Systems GmbH.
For more information:
BCE Special Ceramics GmbH
https://www.bce-special-ceramics.com/
German Institute for Standardization DIN
https://www.din.de/en
Fraunhofer IST
https://www.ist.fraunhofer.de/en.html
MRC Systems GmbH
https://www.mrc-systems.de/en
